1. Field of the Invention
This invention relates to plumbing tools and, more particularly to methods and apparatus for removing a plastic plumbing component that is chemically bonded to a mating component.
2. Description of Related Art
Until the late 1960s, cast iron pipe was used almost exclusively to convey sewer waste from residences and businesses to the main sewer line. Joints were packed with caulking rope and molten lead was poured into the joint to hold the caulking in place. However, after 1970, acrylonitrile-butadiene-styrene (ABS) plastic pipe rapidly replaced cast iron due to much lower material costs and greatly reduced installation costs. A water closet flange, a termination of the toilet waste pipe to which a toilet mounts, which originally had been a solid cast iron piece—replaceable by melting the lead and removing the caulking rope which secured it to the waste pipe—to a much less sturdy part. The new, less-substantial part are either made entirely from ABS plastic, or made partly from ABS plastic and attached to a rotatable sheet metal flange stamped from painted, non-stainless steel. Neither the all-ABS part nor the composite part are designed to last much more than twenty years. A steel flange will eventually rust and break. An ABS flange will deform under pressure and eventually break. Consequently, water closet flanges which were installed in the 1970s are now requiring replacement. Heretofore, replacement of an ABS flange has generally required a splice joint in the waste pipe. If the waste pipe is accessible from below (i.e., via a crawl space or by cutting open a ceiling, the job is manageable. However, if the pipe is embedded in concrete, replacement can be a major job requiring removal and replacement of concrete around the flange and around the waste pipe to which it is connected.
U.S. Pat. No. 5,304,018 to LaVanchy, et al. discloses a plunge cutter for plastic pipe, pipe couplings, and plastic flanges. The plunge cutter has a cylindrical body supporting cutters, a drive shaft, a pilot mandrel for guiding the cylindrical body. The cutters are adjustably mounted in cutter slots formed in the cylindrical body so that the cutters present forwardly facing cutting edges which lie skewed relative to a radius of the cylindrical body. A method for the use of the plunge cutter is also provided.
There are two problems with the design of the LaVanchy, et al. tool. The first is a relatively high cost of manufacture. The body of the cutter must be either cast or machined. The cutters, which must be manufactured separately from the body, must be secured in grooves within the body. The method of construction is relatively labor intensive, relatively complex, and requires a relatively high degree of precision for proper functionality. The second problem with the LaVanchy, et al. tool is that the mounting of the separate cutter blades within the front-facing tubular portion of the body mandates that the thickness of the tubular portion be greater than the thickness of most closet hicker than must be of a thickness that is greater than the thickness of most closet flange couplers. Thus, when a closet flange is embedded within a concrete slab, as is the case with most homes in the Southwestern, Southcentral and Southeastern states, the closet flange cannot be removed without the body of the tool striking the concrete.
For applications where a closet flange is embedded within a concrete slab, it would be desirable if the thickness of the cutting elements of a plunge cutter were thinner than the walls of the closet flange coupler collar.
What is needed is a new plunge cutter which is inexpensive to manufacture, and which may be used to successfully cut away closet flanges, even when they are embedded within a concrete slab. Although the device may be used to remove any type of pipe coupling on a straight section of pipe, the invention would be particularly useful for removing water closet flanges which have become unusable due to rust or breakage. Ideally, a new fitting, coupling or flange could be installed on the pipe, with little or no cleanup, simply by apply a new layer of adhesive and installing the fitting, coupling or flange.